Exhibiting instrument



Dec. 17, 1946. H. M. KIRSCHBAUM EXHIBITING INSTRUMENT Filed Dec. 14, 1942 2 Sheets-Sheet 1 FIG.2.

INVENTOR.

HARRY M. KIRSGHBAUM ATTORNEYS Filed Dec. 14, 1942 2 Sheets-Sheet 2 FIG.4.

Flee;

INVENTOR. HARRY M.K|RSCHBAUM ATTORNEYS Patented Dec. 17, 1946 UNITED STATES PATENT OFFICE EXHIBITING INSTRUMENT Harry M. Kirschbaum, Detroit, Mich.

Application December 14, 1942, Serial No. 468,943

2 Claims. 1

The invention relates to exhibiting means designed for use in connection with various measuring instruments and of that type in which the record is a line or graph formed on a traveling strip by means actuated by a variable electric current. My improved recorder is more particularly intended for recording the oxygen content of the blood as, for instance, that of an aviator during flight at high altitudes, and may be used in connection with such an instrument as that forming the subject matter of my copending application for patent, Serial No. 449,489, filed July 2, 1942. However, the device will be equally useful for other purposes.

It is the object of the invention to obtain a construction adapted for successful operation on a traveling vehicle or in other places where subject to jars, vibration-s or other disturbing conditions. To this end the invention consists, first, in a recording instrument which is unaffected by mechanical movements of its support and further in the peculiar construction as hereinafter set forth.

In the drawings:

Fig. 1 is a plan view of a portion of the recording instrument on one side of a supporting plate, its enclosing casing being omitted;

Fig. 2 is a perspective View of the electromagnetic actuated controlling means on the opposite side of the supporting plate;

Fig. 3 is a section through this controlling means substantially on line 3-3, Fig. 2;

Fig. 4 is a section partly in elevation on line 4-4, Fig. 1;

Fig. 5 is a section on line 55, Fig. l; and

Fig. 6 is an elevation of a portion of the recording strip.

While the instrument for measuring the oxygen content of the blood is not a part of the instant invention and is not illustrated, it may be generally described as including a photo-electric cell which is placed adjacent to tissue of the body as, for instance, the lobe of an ear and is subjected to light which is transmitted through this tissue. Blood that is deficient in oxygen is more opaque to light than oxygenated blood and, consequently, the blood circulating through the capillaries of the tissue where it changes in oxygen content will vary the quantity of light transmitted to the photo cell. This, in turn, in connection with suitable amplifying means will produce a Variable electric current which is used for operating the recorder.

Many instruments heretofore made use a galvanometer as the recording or indicator means.

Such an instrument while very sensitive to electrical changes is also affected by mechanical movements and vibrations so as to be unsuitable for use on a traveling vehicle. I avoid such defeet by the use of electromagnetic means and connected mechanism which is non-sensitive to mechanical movements but will respond to electrical changes, the specific construction being as follows.

A is a permanent magnet which has a central pole member B and a surrounding annular pole member C of unlike polarity. The members B and C are connected at one end by the plate D so as to form in effect a return bent or horseshoe cross section with the opposite ends of the members B and C constituting the poles. Mounted in front of the poles is a member E preferably of dielectric material. On this member is mounted an armature F in the form of a lever which is fulcrumed at one end on a pivot G. H is a resilient member preferably a helical spring which is placed in a housing I secured to the member E. One end. of the spring H bears against the armature F to resiliently oppose its movement toward the poles by the magnetic attraction thereof. The tension of this spring may be adjusted by a screw J which forms an abutment for its opposite end. The member E is mounted on a suitable supporting base plate K through the medium of posts K.

On the opposite side of the plate K is mounted a tubular housing L containing an electric lamp or other source of light and in alignment with this housing is a revoluble drum M. Passing around this drum is a light sensitive strip N which is supplied from a reel 0 and is advanced by a winding reel P rotatable by any suitable means (not shown) such as a spring. Between the drum M and the housing L is an oscillatory member Q which passes through an aperture in the plate K and through a guide bearing R. The end of this member Q is pivotally connected at S to one end of a lever S pivotally fulcrumed at S in a bracket T which is supported from the member E. The opposite end of the lever S bears against the free end portion of the armature F so that any movement of said armature is transmitted through said lever to the member Q. A spring U actuates the lever Q in the opposite direction from that imparted by the armature F.

The member Q is in the nature of a diaphragm or shield which obstructs the light from the source within the housing L but which is provided with a transversely extending narrow slit Q for the passage of light. A second diaphragm or light shield V is placed adjacent to the member Q and has a slit V therethrough which extends transversely to the direction of the slit Q. The combined effect of these two slits is to permit only a pencil of light to pass therethrough and to produce a light spot on the sensitive strip passing over the drum M. Any movement of the member Q in the bearing R will cause this light spot to move transverselyof the-strip N while the advancement of this strip will cause a relative longitudinal movement of the light spot. Consequently, in operation the traveling of the light spot over the sensitive strip will produce a line thereon.

The movement of the armature'F'is caused by a variable current in a coil or helix W which is located to surround the pole portion B and to lie between the same and the annular pole'portion C. This coil has passed therethrough. The electrical current which is supplied from the measuring instrument and any variation in the volume of .this current will produce a corresponding variation in the attractive magnetic force exerted on the armature F. It is, therefore, apparent that where the magnetic attraction is increased the armature will be movedtowards the poles B and C. This, however, by compressing the spring H will increase its resistance until the two forces are brought into. balance. The movement of the armature is transmitted through the step-up lever S to the member Q shifting the latter to a different position. In the same way any decrease in the current volume passed through the coil W will diminish the magnetic attraction and permit the spring H to move the armature F away from the pole and correspondingly movethe member Q, This will produce a line or graph on the strip N which corresponds to variations in strength of the electrical current which, in turn, aleprO- duced by variations in.light impinging on the photo-electric cell caused by variations in the oxygen content of the blood.

To facilitate the interpretation or measurement of the graph, it is advantageous to have parallel lines equally spaced andrunning longitudinally of the strip N. These may be produced by a member X which contains an electric lam X or other source of lightand which has a curved guide way X over which the strip N is tures X through this guide way. 'Thus,ilight passing through these apertures will trace a series of parallel lines which together with the graph line will appear upon the development of the strip.

As above stated, my improved recording instrument is not afiected by vibrations or other mechanical movements of the instrument. This is for the reason, first, that the member Q is held bythe bearing R from any movement other than the longitudinal movement thereof. Second, the armature F is held in fixed position whenever the magnetic force is constant and is balanced by the opposed force of the spring H. This is for the reason that these opposed forces are of *sufiicient magnitude to remain substantially unaffected by mechanical vibrations. Also, as the armature is of comparatively small mass, the inertial force thereof is relatively small.

What I claim as my invention is:

1. An actuating mechanism for exhibiting means adapted to eliminate inaccuracies due to vibration when carried by a moving vehicle comprising a permanent magnet having a central pole and a surrounding annular pole a helix within the space between said poles'for the passage of a variable electric current to correspondingly vary the magnetic intensity, an armature extending across'and spaced from said poles, resilient means for variably opposing the variable magnetic pole on said armature to counterbalance the same in difierent positions of the latter, exhibiting means, and a connection between said armature and exhibiting means.

2. An actuating mechanism for exhibiting means adapted to eliminate inaccuracies due to vibration when carried by a moving vehicle comprising a permanent magnet having a central pole and a surrounding annular pole, a helix within the space between said poles for the passage of a variable electric current to correspondingly vary the magnetic intensity, an armature extending across and spaced from said poles, resilient means for variably opposing the-variable magnetic pole on said armature to counterbalance the same in different positions of the latter, exhibiting means, a member connecting said armature with said exhibiting means, and a bearing with which said member is slida-bly engaged cooperating with said armature and resilient means to resist movement thereof by other force.

HARRY M. KIRSCHBAUM. 

